JPS6221126A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To obtain an inexpensive display device which has good display contrast while using only two pattering masks and simplifying processes greatly by forming a nonlinear resistance element by employing heat oxidation and a transparent electrode. CONSTITUTION:A heat oxidation treatment is carried out at 400-500 deg.C for 5-20min after Ta is sputtered and patterned on a glass substrate, and then an oxide layer 1 is formed on the surface of the Ta film to hundreds of A. Then, ITO is vapor-deposited and sputtered as a transparent electrode material and the upper electrodes of two line electrodes 3a and 3b and picture element electrodes of 4 are formed by one mask. The ITO is not pure metal, but reduced in resistance value and useful as the upper electrodes of the element. Consequently, a sufficient switching element is obtained when made to correspond to the selection and nonselection voltages of a liquid crystal matrix and the liquid crystal display control is improved.

Description

[Detailed Description of the Invention] C. Industrial Application Field] The present invention relates to a liquid crystal display panel, especially an X
The present invention relates to a Y matrix liquid crystal display device.

[Summary of the invention]

The present invention is a portable computer, a liquid crystal display T.
In a liquid crystal display panel used for V, etc., a nonlinear resistance element is formed for each pixel on an electrode substrate, thereby providing a liquid crystal display device with good contrast at low cost.

[Conventional technology]

Nrai fR, which forms a nonlinear resistance element in a liquid crystal display device
J! :shi"ClMXM(MefaJ-Xnttxlα'
tar-Me+αj) elements were known. (B.I.D.
84 D Engineering GI! i8T P, 3Q4) Figure 92 shows the cross-sectional shape of the same M element.

[Problem that the invention seeks to solve]

However, as shown in the same figure, the conventional M-engine M-element
Since two types of metals, Ta3 and Cf4, are required to obtain a MIMIII structure, T, Cr.

Three ITO5 thin film formation and patterning masks are required. Even if a Ta film is formed again at around 070, the number of film formation and patterning steps will not be reduced.

In order to form such a conventional M process M element, film formation and patterning are required three times, which increases the cost. Furthermore, in this example, since the anodic oxidation method is used to form the oxidized 111TcLao+s3, there is a problem that an auxiliary electrode or the like is required to make the oxidation voltage uniform, which complicates the process.

Therefore, in order to solve these conventional problems, the present invention provides a method for forming a custom-made metal-metal oxide nonlinear resistor in a liquid crystal display panel, which requires less number of film formation and patterning steps and uses a simple method. The object of this invention is to obtain a method for forming an oxide film and an electrode.

[Means to solve problems]

In order to solve the above problems, the nonlinear resistance element of the present invention is provided by forming a metal oxide film by thermal oxidation after patterning a metal base film, and further, as an upper electrode of the element.
It is characterized by the use of transparent electrodes.

[Effect]

The element formed by the above process can achieve the same properties as the conventional M process M element by using the underlying metal, the oxide layer formed by thermal oxidation, and the transparent electrode, and the resistance changes depending on the applied voltage. This results in a non-linear "resistance % characteristic" in which the value changes.

[! j! Example]

Embodiments of the present invention will be explained below based on the drawings. In Figure 1, when Ta is sputtered onto a glass substrate and thermally oxidized for 5 to 20 minutes at 400°C to 500°C, hundreds of oxide layers are formed on the surface of the Ta film. After evaporating or sputtering TOT as a transparent electrode material, 2 line electrodes, 3α and 3B02O nonlinear resistance element Q upper electrodes, and 4 pixel electrodes are formed using one mask. 17 mouths are not pure metal,
1 Normally, the M-type M element, which can have a low resistance value and serve well as the upper electrode of the element, has polarity dependence unless the upper and lower oxide layers are made of the same metal, but the present invention has two elements 3α and 3α. This problem is solved by arranging it in series with 36.

Let's explain this using Figure 3.
It shows a cross section taken along line A-A' shown in the figure. First, when current flows from electrode 4α on the line side, 4α (T
O)-3(Tag8c)-2(Ta)-3(Ta0z)
-46(x'ro), and in the case of the ninth order reverse polarity reaching the pixel electrode, the above-mentioned reverse path is followed. In either case, the result is TE-TcLOz-Tc-TaOz-TO, and no difference in positive or negative polarity occurs. Next, actual measurement 111 of the voltage-conductivity of the device obtained by this method is shown in FIG.

In FIG. 4, the size of the device was 20 μm. Two devices were connected in series as shown in FIG. 1 and measured. Generally, a custom M-engine M-element is expressed as a Pooze-1'rttnkelk plot. That is, h (work/V) = β・β0! 1 as nα. xMt square root of the applied voltage, Y1M+t - When taken as the logarithm of the conductivity, it is characterized by the slope β of the straight line and the intercept α of the Y axis.Custom-made elements of the present invention are given by βz from Figure 4.
9. α; 10-11 (Ω″″1) was obtained, and the polarity differences were all the same except for a slight difference on the low voltage side. If the 6 points in Figure 11 are in the 0FIF state and point b is in the ON state, the 0N10FP ratio will be 104 or more, and when the selection of the liquid crystal matrix and the non-operating voltage are adjusted, it will become a sufficient switch knob element and the liquid crystal display contrast will increase. can be improved.

Note that in this example, TO was used as the transparent electrode.
8% G, etc. 17) Similar effects can be obtained using N K 8 A electrodes. In this case, the NKEIA spraying process can be simplified by simultaneously performing thermal oxidation using the heat of the furnace.

〔Effect of the invention〕

As explained above, by forming a nonlinear resistance element using thermal oxidation and transparent electrodes, the present invention requires only two patterning masks compared to the conventional element manufacturing process, greatly simplifying the process. be done. Furthermore, the custom-made element obtained by the present invention exhibits characteristics a comparable to those of conventional M-engineered M elements, and its polarity is at a level that does not pose a practical problem.

Therefore, according to the present invention, it is possible to solve the drawbacks of the conventional active matrix which has good contrast but is expensive, and to realize an inexpensive liquid crystal display device with good display contrast.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a nonlinear resistance element and a pixel electrode according to the present invention, FIG. 2 is a cross-sectional view of a conventional nonlinear resistance element, and FIG.
The figure is a 5-AI sectional view of the DflEL element part of the present invention, No. 4
The figure is a voltage-conductivity characteristic diagram of the nonlinear resistance element of the present invention.
The dotted line indicates the opposite polarity to the solid line. 6 a a a OIF F voltage S, @, ON voltage or more non-bell-shaped collection i> and drawing iΦ stone plane scale Ll! 1 To the east of the house → Do thread body shape bu ■ Good W side of the support rope j Calculation 2 diagram

Claims (5)

[Claims] (1) In a liquid crystal display device consisting of two opposing electrode substrates and a liquid crystal layer held therein, a nonlinear resistance element is provided for each pixel on one of the electrode substrates. Characteristic liquid crystal display device. (2) The liquid crystal display device according to claim 1, wherein the nonlinear resistance element is composed of a metal, an oxide layer of the metal, and an electrode layer. (3) The metal of the nonlinear resistance element is Ta, Ti, Mo,
The liquid crystal display device according to claim 1, characterized in that the material is Co, Ni, Fe, W, Zn, Cu, or Al. (4) The liquid crystal display device according to claim 1, wherein the metal oxide layer of the nonlinear resistance element is formed by thermal oxidation. (5) The liquid crystal display device according to claim 1, wherein the electrode of the nonlinear resistance element is a transparent electrode.